The present invention relates to reduction gear units, and more particularly, to reduction units employing worm gear components.
Worm gear reduction gear units are well known. For example, a worm gear reduction unit employing two sequential worm units at right angles to each other is conventional. Such a unit has a first worm, directly driven by a motor, driving a pinion which is coaxial with a second worm. The second worm drives a final gear used to drive some mechanical element.
In the conventional double-worm reduction unit, assembly of the second worm is difficult. For example, the second worm may have an intermediate spring provided about the shaft, such that the overall length of the shaft may be shortened and then inserted between two mounting holes provided in a monoblock support, where the shaft is allowed to expand and the second worm is thereby assembled in the block. Alternatively, the second worm may be provided with rectangular bearing blocks at both ends of the shaft, and the bearing blocks may be slid into a monoblock housing and adhered, thus securing the worm.
In both cases, assembly of the double-worm reduction unit requires extra parts, and is inconvenient to carry out. Furthermore, when the elements of the reduction unit are extremely small, such as those used in cameras or other precision equipment, utilizing miniature spring-loaded worm elements or bearing blocks is difficult and time-consuming.